Nanostructured sorbent materials for capturing environmental mercury vapor

ABSTRACT

The present invention is a method and material for using a sorbent material to capture and stabilize mercury. The method for using sorbent material to capture and stabilize mercury contains the following steps. First, the sorbent material is provided. The sorbent material, in one embodiment, is nano-particles. In a preferred embodiment, the nano-particles are unstabilized nano-Se. Next, the sorbent material is exposed to mercury in an environment. As a result, the sorbent material captures and stabilizes mercury from the environment. In the preferred embodiment, the environment is an indoor space in which a fluorescent has broken.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is related to and claimspriority from PCT International Patent Application No. PCT/US08/079,048,filed on Oct. 7, 2007 under 35 U.S.C. §371, and earlier filed U.S.Provisional Patent Application No. 61/049,848 filed May 2, 2008 and U.S.Provisional Patent Application No. 61/032,375 filed Feb. 28, 2008, allof which are incorporated herein by reference.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under 0930303 awarded byNational Science Foundation and P42 ES013660 awarded by NationalInstitutes of Health. The government has certain rights in theinvention.

BACKGROUND OF THE INVENTION

The present invention generally relates to a method and materials formercury capture. More specifically, the present invention relates to amethod and materials for capturing mercury using sorbent materials.

Mercury is considered by the government to be an air toxic pollutant.Mercury is of significant environmental concern because of its toxicity,persistence in the environment, and bioaccumulation in the food chain.Elemental mercury is volatile and is therefore released as a vapor intothe environment from a variety of anthropogenic sources. Atmosphericdeposition of mercury is reported to be the primary cause of elevatedmercury levels in fish found in water bodies remote from known sourcesof this heavy metal.

Mercury can enter into the environment through the disposal (e.g.,landfilling, incineration) of certain products. Products containingmercury include: auto parts, batteries, fluorescent lamps, medicalproducts, thermometers, flat-panel televisions and thermostats. Due tohealth concerns, toxic use reduction efforts are cutting back oreliminating mercury in such products. For example, most thermometers nowuse pigmented alcohol instead of mercury.

Fluorescent lamps are mercury-vapor electric discharge lamps, and mostcontain from 1 to 10 mg of mercury depending upon the type offluorescent lamp. Much of the mercury in new lamps is in the elementalstate and being volatile can be released into the atmosphere when thefluorescent lamp is broken.

Currently, 300 million CFLs (compact fluorescent lamps) are sold peryear. In the U.S., projections suggest that there will be at least 3billion CFLs in U.S. homes in five years with an ultimate capacity of 4billion. The main cause for the increase in sale of these CFLscontaining mercury is their energy efficiency.

Broken CFLs can pose an immediate health hazard due to the evaporationof mercury into room air. Inhalation exposure is a concern as 80% ofinhaled mercury is physiologically absorbed.

Currently, there is no reliable method or device for capturing andstabilizing mercury found in consumer products, such as CFLs. CFLs arebeing disposed of by consumers by a variety of methods across the UnitedStates. Many consumers have the option of disposing of these products inthe same way they dispose of other solid waste. The EPA has reportedCFLs are being disposed in municipal waste landfill, recycling centers,municipal waste incineration, and hazardous waste disposal.

Most florescent bulb recyclers in the United State employ the dryrecycling process which generates four products: mercury-contaminatedphosphor powder, mercury-contaminated filters, crushed glass, andaluminum end caps. The dry recycling process is a system which operatesunder negative pressure to minimize mercury emissions to the atmosphere.The spent CFLs are first broken. During crushing, a vacuum systemcollects the mercury vapor and the crushed materials including phosphorpowder which contains most of the mercury. The mercury vapor is usuallycaptured by carbon filters during crushing. Mercury-contaminatedphosphor powder and carbon filters are placed in a retort to vaporizethe mercury and collect it for reuse. The separation process employed bymost lamp recyclers cannot remove phosphor powder and mercury on lampglass completely. See M. Jang et al., “Characterization and capturing ofmercury from spent fluorescent lamps,” Waste Management, Vol. 25 (2005).

Three processes are most important for the decontamination of CFLresidues: (i) a thermal process (ii) a chemical process involvinglixiviation by aqueous solutions and (iii) stabilization. The complexityof these process, the necessity of multiple steps, the utilization ofchemical reagants, and especially the generation of effluents thatrequire adequate treatment are the disadvantages of these processes. SeeW. A. Durão Jr. et al., “Mercury Reduction studies to facilitate thethermal decontamination of phosphor powder residues from spentfluorescent lamps”, Waste Management (2007).

The U.S. Environmental Protection Agency recommends that, in the absenceof local guidelines, fluorescent bulbs be double-bagged in plastic bagsbefore disposal. The used or broken CFLs are placed in two plastic bagsand put it in the outside trash, or other protected outside location,for the next normal trash collection. However, the double-bagging ofbroken CFLs will not prevent the release of mercury vapor into the airwhen the bulbs are compromised according to recent data from the MaineDepartment of Environmental Management.

In addition, there is no reliable and efficient method for cleaning upaccidentally broken CFLs in a consumer's home. Today, if a CFL isbroken, the shards of glass can be picked up by hand but somemercury-containing phosphor typically spills onto the surface causingthe breakage site to continue to emit mercury into the air for hours ordays causing a potential health risk, especially in the case of pregnantwomen or young children.

It would therefore be desirable to provide a method of safely andeffectively disposing of mercury-containing products, such as CFLs. Inaddition, there is a need to capture and stabilize volatile mercury toprevent its release into room air when consumer products such as CFLsare broken. Finally, there is a need to provide materials or methods toallow for the safe disposal of the various pieces of broken consumerproducts such as CFLs.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present invention preserves the advantages of priorart methods and materials for mercury capture and stabilization. Inaddition, it provides new advantages not found in currently availablemethods and materials of mercury capture and stabilization and overcomesmany disadvantages of such currently available methods and packagingmaterials for mercury capture and stabilization.

The present invention is a method and material for using sorbentmaterials to capture and stabilize mercury. The packaging materials orpackage contains sorbent materials to capture and stabilize mercury. Thesorbent materials may be nano-particles or other materials used tocapture and stabilize mercury. The nano-particles are selected from agroup consisting of: nano-Cu, nano-Ag, nano-Se, nano-5, nano-Ni,nano-Zn, nano-WS₂ or any nano-particle used for the capturing ofmercury. In a preferred embodiment, the nano-particles are unstabilized,colloidal nano-Se. Other materials that may be used as sorbent materialinclude micro-scale powder, solutions, soluble compounds, activatedcarbon, S-impregnated activated carbon, or other impregnated orchemically modified activated carbon products.

The package or packaging for products containing mercury having sorbentmaterials effective for capturing and stabilizing mercury and a carriermaterial which forms a part of a package. The sorbent materials arecarried on the carrier material. It is also desirable to position thesorbent materials in a location advantageous for capturing andstabilizing mercury vapor emitted from the product.

The package or packaging material contains a carrier material. Thecarrier material may either be a porous or non-porous solid, or a gel orsolvent. For example, the carrier material may be a liner within thepackage. In one embodiment, the carrier material may be selected from agroup consisting of: cardboard, textiles, Styrofoam, paper, and plastic.It should be noted that this list is not exclusive and there areadditional materials used as a carrier material.

The carrier material will contain sorbent material. For example, thecarrier material is impregnated, coated, sprayed, injected, dipped, ordispersed with the sorbent material. In addition, the packaging maycontain a protective layer for preventing contact with the sorbentmaterial by a user. The protective layer lies between the sorbentmaterial of the packaging and the points of potential contact withconsumers and users.

A packaging is used for bulbs containing mercury. The packaging forbulbs may contain an active layer and a barrier layer. The active layerhas a top surface and a bottom surface. The active layer containssorbent materials for capturing and stabilizing mercury. A barrier layerhas a top surface and a bottom surface. The barrier layer is anon-porous material situated on the top surface of the active layer toprevent the passage of mercury across the barrier layer.

Optionally, a protective layer may underlie the bottom surface of theactive layer. The protective layer is a porous material to preventcontact with the sorbent material of the active layer. When the bulbreleases mercury, the mercury is absorbed or reacts with the sorbentmaterial of the active layer and the barrier layer prevents the releaseof the mercury giving time for the reaction with the sorbent materials.

A method for using packaging containing sorbent material to capture andstabilize mercury contains the following steps. First, a packaging isprovided that contains sorbent materials for capturing of mercury.Second, the packaging is positioned over the mercury spillage site orbreakage site to capture and stabilize the mercury. As a result, thesorbent material of the packaging absorbs the mercury. The advantage ofusing packaging as the vehicle for distributing the sorbent material isthat it is part of existing product flows and is distributed with theproducts that may cause the exposure.

In another embodiment, a kit containing items having sorbent materialsmay be provided to capture and stabilize mercury. The items are selectedfrom a group consisting of: cloth, bags, packaging, package, linings,gloves, paper towels, cardboard, squeegee, eyedropper, duct tape,shaving cream, paint brush, flashlight, sorbent materials in powderedform, and combinations thereof.

The method for using sorbent materials to capture and stabilize mercurycontains the following steps. First, the sorbent material is provided.The sorbent material, in one embodiment, is nano-particles selected froma group consisting of: nano-Cu, nano-Ag, nano-Se, nano-S, nano-Ni,nano-Zn, and nano-WS₂ or any material used for the capturing of mercury.In a preferred embodiment, the nano-particles are unstabilized,colloidal nano-Se.

The sorbent material is provided in different forms. In one form, thesorbent materials are a powder used for dispersing onto a mercuryspillage site. In another embodiment, the sorbent materials areimpregnated, coated, sprayed, dispersed, dipped, or injected onto acarrier material. The carrier material may be either a non-porous orporous carrier material, such as cardboard.

Next, the sorbent materials are exposed to mercury in an environment.The environment can be either indoors or outdoors. For example, theindoor environment may be a building, office, dentist's office,laboratory, recycling center, store, residential or commercial building,warehouse, shipping vessel, shipping container, recycling center,container, packaging, storage space, and vehicle or any otherenvironment where mercury is found. For the outdoor environment, it maybe a landfill, stadium, office park, or any other outdoor environmentwhere mercury is found. When the sorbent materials are exposed tomercury, the nano-particles capture and stabilize mercury of theenvironment.

It is therefore an object of the present invention is to provide amethod using sorbent materials to capture and stabilize mercury.

It is a further object of the present invention is to provide sorbentmaterials on a carrier material to capture and stabilize mercury.

Another object of the present invention is to provide a packaging of aproduct that contains sorbent material for capturing and stabilizingmercury in that product.

A further object of the present invention is to provide a productcontaining sorbent material for capturing and stabilizing mercury.

Other objects, features and advantages of the invention shall becomeapparent as the description thereof proceeds when considered inconnection with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are characteristic of the method for mercurycapturing are set forth in the appended claims. However, the method formercury capturing, together with further embodiments and attendantadvantages, will be best understood by reference to the followingdetailed description taken in connection with the accompanying drawingsin which:

FIG. 1 is a perspective view of packaging for bulbs containing sorbentmaterials;

FIG. 2A is a cross-sectional view of packaging containing sorbentmaterials to capture and stabilize mercury;

FIG. 2B is a cross-sectional view of packaging containing sorbentmaterials to capture and stabilize mercury;

FIG. 3 is a perspective view of a bulb containing sorbent materials;

FIG. 4A is graph showing mercury vapor release characteristics for twobrands of compact fluorescent lamps;

FIG. 4B is a graph showing mercury evaporation rate as a function of gasflow rate over the compact fluorescent lamps;

FIG. 5 is a graph shows a curve for fixed-bed sorbent evaluationsexperiments;

FIG. 6 is a table of low-temperature mercury vapor sorbents;

FIG. 7 is a graph showing standard Hg adsorption capacities forelemental sulfur nanotubes and sulfur powder as a function of adsorptionreaction temperature;

FIG. 8A is an SEM micrograph of nano-silver particles before vacuumannealing at 500 degrees Celsius;

FIG. 8B is an SEM micrograph of nano-silver particles after vacuumannealing at 500 degrees Celsius;

FIG. 9A is an illustration depicting colloidal synthesis ofBSA-stabilized nano-SE (left) and unstabilized nano-SE (right);

FIG. 9B is a graph showing particle size distributions in aqueous mediaby dynamic light scattering;

FIG. 9C is an graph showing Hg-uptake kinetics under standardconditions;

FIG. 10 is a graph comparing mercury adsorption capacity of thesorbents;

FIG. 11 is a graph showing effect of in situ sorbents on mercury vaporrelease following fracture of a compact fluorescent bulb at roomtemperature;

FIG. 12 is a perspective view of a recycling container with a cut-outview of sorbent material contained therein;

FIG. 13 is a perspective view of a packaging containing sorbent materialfor a flat screen television;

FIG. 14 is a perspective view of an air purifier having a filtercontaining sorbent material;

FIG. 15 is a block diagram of a method for capturing mercury usingsorbent material;

FIG. 16 is a block diagram of a method for using a packaging containingsorbent material to capturing mercury;

FIG. 17 is a perspective view of a broken bulb and a user removing thebroken bulb;

FIG. 18 is a perspective view of a user placing the broken bulb of FIG.17 into a container lined with sorbent material;

FIG. 19 is a perspective view of a user dispersing a powdered form ofthe sorbent material over mercury spillage site;

FIG. 20 is a perspective view of the packaging positioned over themercury spillage site with an object resting thereupon to facilitatesuppression of the mercury;

FIG. 21 is a kit containing at least one item having sorbent materialsfor capturing mercury; and

FIG. 22 is an exploded view of a nonabsorbent cloth.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiment is generally directed to a novel and unique method andmaterial for capturing and stabilizing mercury. In particular, thepresent invention is a method and material containing sorbent materialsto capture and stabilize mercury. The method and packaging material ofthe present invention provides a safe and effective disposal of themercury contained within products.

The present invention is a method and material for using sorbentmaterials to capture and stabilize mercury. The packaging materials orpackage contains sorbent materials to capture and stabilize mercury. Thesorbent materials may be nano-particles or other materials used tocapture and stabilize mercury. The nano-particles are selected from agroup consisting of: nano-Cu, nano-Ag, nano-Se, nano-5, nano-Ni,nano-Zn, nano-WS₂ or any nano-particle used for the capturing ofmercury. In a preferred embodiment, the nano-particles are unstabilized,colloidal nano-Se. Other materials that may be used as sorbent materialinclude micro-scale powder, solutions, soluble compounds, activatedcarbon, impregnated activated carbon, or other impregnated or chemicallymodified activated carbon products.

In a preferred embodiment, the nano-particles are unstabilized,colloidal nano-Se. The nano-particles capture and stabilize mercury fromthe environment when exposed to the mercury vapor. With regard tonano-Se, it is known in the art the following chemical reaction:Se+Hg→HgSe.Based upon the experiments shown below, colloidal, unstabilized nano-Secapture and stabilizes mercury better than any other nano-particle.

The package or packaging for products which contain mercury containssorbent materials effective for absorbing and reacting with mercury anda carrier material which forms a part of a package. The sorbentmaterials are carried on the carrier material. It is also desirable toposition the sorbent materials in a location advantageous for absorbingmercury vapor emitted from the product. The package or packaging forproducts may also serve to temporarily contain the mercury or block itsdispersion into room air so that it can be captured and stabilized bythe sorbent material.

The carrier material has many different forms. The carrier material mayeither be porous or non-porous material. For example, the carriermaterial may be a liner within the package. The carrier material may beselected from a group consisting of: cardboard, textiles, Styrofoam,paper, and plastic. The material is impregnated, coated, sprayed,injected, dipped, or dispersed with the sorbent materials. In addition,the packaging may contain a protective layer for preventing contact withthe sorbent materials by a user. The protective layer underlies thesorbent materials of the packaging.

For example, the package 100 is used for bulbs containing mercury asshown in FIG. 1. More specifically, fluorescent bulbs are known tocontain mercury, such as CFLs. It is contemplated that the sorbentmaterials may be used in packaging for fluorescent bulbs, separatesheets or linings in the packaging for fluorescent bulbs, or bags linedwith sorbent materials contained within the fluorescent bulbs.

The packaging 100 includes porous and non-porous materials. For example,the packaging may include linings, bags, containers, blankets, cloths(FIG. 22), pouches, cardboard, and any other material used in packaginga product or good. For example, a porous cloth (FIG. 22) is dipped intosorbent material solution. When the porous cloth is sufficiently dried,the cloth can be placed over mercury spillage sites to capture andstabilize mercury. In a preferred embodiment, the packaging includesboth a porous layer containing sorbent material and a non-porous layerto prevent mercury from diffusing through and away while a reactiontakes place with the sorbent material.

Referring to FIGS. 2A-2B, the packaging material 10 for the bulbscontains multiple layers 20,30,40. It should be noted the packaging forbulbs may contain at least one active layer 20 containing sorbentmaterials to capture and stabilize mercury. Referring to FIG. 2A, thepackaging material for bulbs may contain an active layer 20 having a topsurface and a bottom surface and containing the sorbent material. Thepackaging material 10 may also include a barrier layer 30 which has atop surface and a bottom surface. The barrier layer 30 has a non-porouscarrier material and is situated on the top surface of the active layer20 to preventing the diffusion or flow of mercury through themulti-layer structure. The barrier layer 30 prevents the passage ofmercury to allow time for reaction with the sorbent material of theactive layer 20.

Referring to FIG. 2B, a protective layer 40, optionally, may underliethe bottom surface of the active layer 20. The protective layer 40contains a porous carrier material to prevent contact with the sorbentmaterial of the active layer 20. When the bulb releases mercury, themercury is absorbed or reacts with the sorbent material of the activelayer 20 and the barrier layer 30 prevents the release of the mercurygiving time for the reaction with the sorbent materials.

Referring to FIG. 3, a bulb 200 may also contain sorbent materials neara bottom portion of the bulb to capture and stabilize the mercury. Inthis embodiment, the sorbent materials are contained underneath thebottom plastic cap 210 of the bulb 200. The plastic cap 210 definesholes 220 for allowing mercury to contact the sorbent materials.

Experiments were conducted to measure the adsorption capacity of each ofthe sorbent materials. Adsorption or capturing capacities ofnano-particles range over seven orders of magnitude, from 0.005 ug/g (Znmicropowder) to >188,000 ug/g (unstabilized nano-Se) depending onsorbent chemistry and size. Unstabilized nano-selenium in two forms (drypowder and impregnated cloth) was used in an experiment for the in situ,real-time suppression of Hg vapor escape following CFL fracture.

Materials and Methods for Adsorption Capacities of Nano-ParticlesCompact Fluorescent Lamps and Hg Release Characteristics

Two different brands of compact fluorescent lamps were purchasedcommercially: a 13 W and 9 W device containing 4.54 mg and 5.0 mg ofmercury respectively. To characterize the release of Hg vapor underambient conditions, the bulbs were catastrophically fractured inside aflexible Teflon cylinder and the Hg vapor transported away by a meteredflow of nitrogen passed to a gold amalgamation atomic fluorescentvapor-phase mercury analyzer (PSA model 10.525). Additional experimentswere carried out on used bulbs at the point of burnout collected fromresidences and retail recycling centers. In addition, proof-of-principleexperiments demonstrating in situ capture were carried out using varioussorbents.

A test sorbent material was added to the Teflon cylinder along with theCFL, the bulb fractured, and the system sealed for 24 hours to simulatecontainment in a dedicated disposal bag or modified retail package. Atthe end of this period, nitrogen flow was initiated and the effluent gaswas analyzed for Hg vapor release.

Sorbents

A variety of carbon materials were used in this study including DarcoFGL activated carbon (Norit, 550 m2/g), a granulated activated carbonfrom Alfa Aeser (900 m2/g), Cabot M-120 carbon black (38 m2/g) a sulfurimpregnated carbon sample (HgR, Calgon Carbon, 1000-1100 m2/g) and amesoporous carbon (144 m2/g). All surfaces areas are BET values measuredat Brown (Autosorb-1, Quantachrome Instruments) or supplied bymanufacturer.

Sulfur nanotubes were synthesized at Brown by dipping 200 nanometerchannel aluminum templates in a 50 mass-% solution of Sigma Aldrich 100mesh commercial sulfur and CS2. The loaded templates were dried andexcess sulfur removed from the template top with a razor blade. Thealuminum templates were etched overnight with 2M NaOH solution. The5-nanotube samples were washed twice with 1 M NaOH, twice with 0.5M NaOHand four times with DI water followed by centrifugation and oven dryingat 60° C.

Copper, both micro- and nanoscale metal particles, were obtained fromSigma Aldrich (<10 μm) and Alfa Aesar (20-40 nm, 13 m2/g) respectively.Nickel microsized metal powder was obtained from Sigma-Aldrich (˜3 μmdiameter). Nickel nanoparticles were obtained from Alfa Aesar (15-625nm, 15.9 m2/g). Zinc metal powders were obtained from Sigma-Aldrich(microproduct<10 μm and nanoproduct<50 nm, 3.7 m2/g). Silvernanoparticles were obtained from Inframat Advanced Materials (100-500 nmand 1.2 m2/g as received). All the metal powders were studied shortlyafter unpacking unless noted as processed in some way. Microsizedmolybdenum sulfide and tungsten sulfide powders were obtained from SigmaAldrich (both<2 μm). Tungsten disulfide nanoparticles were obtained fromNanostructured & Amorphous Materials, Inc. (BET area of 30 m2/g).

Amorphous nanoselenium was prepared using a 4:1 molar mixture ofglutathione (GSH, reduced form, TCI America) and sodium selenite(Na2SeO3, Alfa Aesar) solution. Glutathione reduces sodium selenite toform seleno-diglutathione (GSSeSG), which decomposes to elementalselenium as upon sodium hydroxide titration. In the presence of bovineserum albumin (BSA, Sigma-Aldrich) the reaction gives a stabilizednanoselenium dispersion. For mercury capture experiments, the solutionsof nanoselenium were divided in 1.5-2 ml aliquots and freeze dried toprevent any thermal effects of heat drying. The nanoselenium sampleswere palletized by centrifugation (13,000 rpm, 10 min) beforefreeze-drying. These freeze dried aliquots and Seimpregnated cloth,which was prepared by soaking a 15″×17″ Kimwipe in the amorphousnanoselenium solution and dried at room temperature, were used for thein-situ mercury release experiments. A commercial selenium sample wasobtained in the form of pellets (J.T. Baker) and crushed to obtain Sepowder of 2-200 μm.

Mercury Adsorption Capacity Measurements

Elemental mercury vapor was generated in Ar (300 cc/min) at 60±3 μg/m3using the Hg CAVKIT 10.534 (PS Analytical, Ltd) and passed through afixed bed of sorbent resting on a Pyrex fritted disk inside a tubularPyrex reactor. The exit Hg concentration was monitored semi-continuously(3.8 min sampling time) by atomic fluorescence using the Sir Galahad II(PS Analytical, Ltd).

Results and Discussion

FIGS. 4A-4B shows time-resolved mercury release data from two CFLmodels. The release is initially rapid producing vapor concentrationsfrom 200-800 μg/m3 during the first hour, which far exceed the OSHAoccupational limits. The release decays on a time scale of hours andcontinues at significant rate for at least four days (data beyond 24 hrsnot shown). It has been suggested that the initial high rate is due toHg existing in the lamp vapor phase, but a simple calculation shows thisto be impossible. Saturated Hg vapor (15,000 μg/m3) in a typical lampvolume (50 ml) corresponds to only 0.65 μg of vapor phase Hg, which ismuch less than the actual mercury release during the first hour, 12-43μg. The majority of Hg in a CFL must be in a condensed phase and mercuryrelease from CFLs is primarily due to desorption/evaporation phenomenainvolving this condensed-phase mercury. FIGS. 4A-4B also compares theactual CFL release with the evaporation of a free Hg droplet under thesame set of conditions. The actual CFL release exceeds the release froma free Hg droplet of equal mass (see FIG. 4A-4B), which likely reflectsthe much larger surface area of the adsorbed phase (on the phosphor, endcaps, and/or glass) relative to the single drop.

Referring to FIGS. 4A and 4B, mercury vapor release characteristics fortwo brands of compact fluorescent lamps following catastrophic fractureat room temperature. A: Hgvapor concentrations and release ratescompared to evaporation from a free mercury drop. The free drop releaserate is corrected for differences in the Hg mass between the drop andthe bulb for two limiting cases: convective mass transfer at constantmass transfer coefficient (rate˜Area˜mass⅔) and diffusion dominated masstransfer from a drop (rate˜K*Area˜mass⅓). The total Hg released after 24hrs is 504 μg (13 W model) and 113 μg (for 9 W) by integration, whichare 11.1% and 1.9% of the total Hg content specified by the vendors,respectively. Over 4 days (extended data not shown) the 13 W bulbreleased 1.34 mg or 30% of the total Hg. B: Mercury evaporation rate asa function of gas flow rate over the broken lamp showing a weakinfluence of convection.

Similar release patterns but lower amounts were seen for spent bulbs(example result: 90 μg in 24 hrs) or from the fracture site of a newbulb after glass removal to simulate cleanup. Removing large glassshards by hand after breakage on a carpet, did not eliminate Hg release,but reduced it 67% relative to the data in FIG. 4A-4B. The remaining(33%) release from the fracture site is believed to be primarilyassociated with spilled phosphor powder, which is known to be theprimary site for adsorbed Hg partitioning in fresh bulbs.

Sorbent Synthesis, Characterization and Testing

Because mercury vapor capture on solids occurs by adsorption orgas-solid reaction where kinetics and/or capacities typically depend onsurface area, we hypothesized that high-area, nanoscale formulations ofcommon mercury sorbents (involving carbon, sulfur, metals, sulfides, andselenium) will show enhanced performance This section evaluates a largeset of new nanomaterial sorbents for ambient temperature Hg vaporcapture and compares their performance to conventional microscaleformulations of the same materials. FIG. 5 shows an example breakthroughcurve that is the raw output of the fixed-bed sorbent tests. Integratingthe area between the baseline inlet (60 μg/m3) and the outletconcentration curve and dividing by sorbent mass yields a capacityreported in μg-Hg/g-sorbent.

Referring to FIG. 5, an example breakthrough curve in our fixed-bedsorbent evaluation experiments is shown. Time scales range from 20minutes to 184 hrs depending on specific behavior of the sorbent inquestion.

FIG. 6 shows a complete list of the sorbents and their Hg capacitiesunder our standard conditions (60 μg/m3 inlet stream), and the followingsections discuss the results by sorbent class.

Here we choose a convenient templating route to obtain small quantitiesof nanostructured sulfur for sorbent testing. FIG. 8 shows themorphology and sorption behavior of sulfur nanotubes fabricated byspontaneous infiltration of CS2/S solutions into nanochannel aluminatemplates followed by solvent evaporation and chemical etching of thetemplate. The sulfur nanotubes show a 90-fold increase in surface areaand a 24-fold increase in Hg capacity over conventional powdered sulfur.The total captured Hg is much less than the HgS stoichiometric limit andmuch less than even surface monolayer capacity, and the capacitiesincrease with increasing temperature. These results indicate akinetically-limited chemisorption/reaction on active sites thatrepresent a small fraction of the nanotube surfaces.

Metals and Metal Sulfides

Here we experiment with available nanoparticles as room temperature Hgsorbents and compare them to conventional microscale powders (see FIG.7). Mercury capacities vary greatly with chemistry (Ag>Cu>Ni>Zn) and foreach metal are significantly enhanced by nanosynthesis. The rank orderparallels the standard free energies for metal oxidation, nM+½O2-->MnO2(Ag2O: ΔG°f=−9.3 kJ/mol; CuO: ΔG°f=−133.5 kJ/mol; NiO: ΔG°f=−216 kJ/mol;ZnO: ΔG°f=−318.5 kJ/mol) and (complete) oxidation of copper is shown togreatly reduce its sorption activity (31.8 to 4.3 μg/g).

Interestingly, copper metal activity is observed to increase modestly asthe fresh metal nanoparticles age in the atmosphere, which may suggestelevated activity for partially oxidized surfaces. The nanometalcapacities represent from about 10-6 (Zn) to 35% (Ag) of theoreticalmonolayer coverage on the nominal outer surfaces indicating that theprocess is far from reaching stoichiometric alloy formation—even in anouter shell—and the reactions are limited to specific active surfacesites under these low temperature conditions. Among these metalsorbents, nano-silver (see FIG. 4) is potentially attractive as ahigh-capacity sorbent (capacities up to 8510 μg/g) for room temperatureapplications like CFL capture. Annealing nano-silver reduces both itssurface area and Hg capture capacity (FIG. 8A-8B and FIG. 6).

Referring to FIGS. 8A-8B, SEM images of nano-silver particles before(FIG. 8A) and after (FIG. 8B) vacuum annealing at 500° C. In preliminaryexperiments we found WS2 to be significantly more reactive than MoS2(both conventional powders) and therefore were motivated to test WS2nanoparticles as potential high-capacity sorbents. In this casenanosynthesis offered no significant advantage and none of the metalsulfides appear among the most active and useful low-temperaturesorbents in FIG. 6.

Carbon Materials

Activated carbons are widely used to capture mercury vapor and theirperformance can be enhanced by surface modification with sulfur,halogen, or oxygen-containing functional groups. Mercury capture oncarbon is a combination of physical adsorption (dominant on unmodifiedcarbons at low temperature) and chemisorption (dominant at elevatedtemperature or on chemically modified carbons). Because carbons arecapable of developing extensive internal surface area, there is littlemotivation to enhance the external surface area through nanosynthesismethods. Here we evaluate carbons as readily available referencematerials that are market relevant benchmarks for the new nanosorbents.FIG. 6 shows low to modest capacities on carbons (0.45-115 μg/g) withthe exception of the S-impregnated material (2600 μg/g) which afterselenium (see next section) is the best commercially available sorbentin this study.

Selenium

Selenium has an extremely high affinity for mercury. In the body itsequesters mercury into insoluble and metabolically inactive mercuryselenides and by this mechanism is protective against mercuryneurotoxicity. Its antioxidant nature helps to protect against mercuryinduced DNA damage. In the environment the stable sequestration ofmercury by selenium may reduce its mobility, bioavailability, andeco-toxicity. Strong Hg/Se binding may be key to understanding thebiological and environmental behavior of both mercury and selenium.There are few published studies of selenium-based mercury vapor capture,though selenium has been used in Hg removal from off gases in sulfideore processing and is being considered for Hg stockpile stabilizationand long-term storage. The presumed capture mechanism is reaction toHgSe (ΔG°f=−38.1 kJ/mol). Here we focus on amorphous nanoselenium, whichhas received recent attention in chemoprevention, but has not to ourknowledge been used for Hg vapor capture at low temperatures. FIGS.10A-10C shows the colloidal synthesis of nanoselenium, the particle sizedistributions, and the mercury capture behavior of competing Se forms.The original synthesis method uses glutathione (GSH) as a reductant andbovine serum albumin (BSA) as a surface stabilizing agent to achievevery small particles in colloidal suspension. Surprisingly theBSA-stabilized nano-Se has a lower capacity than conventional Se powderdespite much smaller particle size (6-60 nm vs. 10-200 μm). Wehypothesized that the protein stabilizer (BSA) either blocked Hg accessto the Se surfaces or chemically passivated the surfaces throughSe-thiol interactions. We therefore removed the BSA to make“unstabilized nano-Se,” which FIGS. 10A-10C shows to have a remarkablyhigh Hg sorption capacity and much faster kinetics than conventionalmicro-Se. Mercury uptake continues over very long times, and a 184 hrexperiment was necessary to approach the end state, at which point theunstabilized nano-Se had adsorbed 188,000 μg-Hg/g or approximately 20%Hg/Se mass ratio. XRD analysis shows both the micro-Se and unstabilizednano-Se are amorphous in agreement with the conventional wisdom thatelemental selenium obtained by colloidal route is amorphous.Interestingly, there is a region of increasing capture rate indicatingan autocatalytic behavior for both the Se micropowder and theunstabilized nanoselenium.

Referring to FIGS. 9A-9C, synthesis, particle size distributions, andHg-uptake kinetics of competing forms of selenium. A: colloidalsynthesis of BSA-stabilized (left) and unstabilized (right) nano-Se. B:Particle size distributions in aqueous media by dynamic lightscattering, C: Hg-uptake kinetics under standard conditions (60 μg/m3).

Comparison of Sorbents

FIG. 10 shows a comparison of the new and reference sorbents in thisstudy. The right-hand axis gives the amount of sorbent required tocapture 1 mg of Hg vapor, typical of CFL release. Some common sorbentssuch as powdered S or Zn require enormous amounts of material (>10 kg!)to treat the vapor release from a single CFL and most of the sorbentsrequire amounts that are not attractive for incorporation into consumerpackaging (>10 g). A small number of sorbents (nano-Ag, S-impregnatedactivated carbon and two selenium forms) have capacities that shouldallow <1 g of sorbent to be used. The most effective sorbent isunstabilized nano-Se, which can capture the contents of a CFL withamounts less than 10 mg. This capacity corresponds to about fivemonolayer equivalents indicating significant subsurface penetration ofmercury into selenium nanoparticles (unlike the other sorbents). Thecapacity is still only about 7% of the bulk stoichiometric conversion toHgSe, however, indicating the potential for further capacity improvementwithin the Se-based sorbent systems.

Referring to FIG. 10, a comparison of the best-in-class sorbents in thisstudy: left axis: standard Hg adsorption capacity; right axis: amount ofsorbent required for capture of 1 mg Hg vapor typical of the totalrelease from a single CFL over a three-day period.

In Situ Capture of CFL Mercury

Although the amount of Hg released from CFLs on fracture is small(typically <1 mg), some sorbents have sufficient capacity to sequesterit all at room temperature for practical application (see FIG. 10). Forin situ capture where the sorbent is supplied to consumers in the formof a safe disposal bag, impregnated cloth, or modified retail package,only nano-Ag, selenium forms or sulfur-impregnated activated carboncould be used in reasonable quantities. The concept of in situ captureis demonstrated below, here “treatment” is defined as sealing thefractured CFL and sorbent in a confined space for 24 hours, thenremoving the sorbent and measuring the residual vapor release.

Referring to FIG. 11, a graph shows effect of in situ sorbents onmercury vapor release following catastrophic fracture of a CFL at roomtemperature. Top curve: no sorbent; Bottom curves: same CFL broken inpresence of sulfur-impregnated activated carbon (1 g HgR) andunstabilized nano-selenium (10 mg) either as dry nano-powder orimpregnated cloth. The integrated mercury released over the course ofthis experiment is 113 μg (untreated lamp), 20 μg (1 g HgR treatment),1.6 μg (Se in vials), and 1.2 μg (Se-impregnated cloth). The commercialsulfur-impregnated activated carbon reduced the mercury release by 83%over the untreated bulb, making it a viable candidate for in situcapture of mercury vapor. Moreover, the low cost and low toxicity ofthis material make it an attractive option for consumer use. Even betterperformance was exhibited by the unstabilized nano-selenium, whichdecreased the mercury release by 99% over an untreated bulb, regardlessof the application method, and with 100-fold less sorbent mass. Nearlycomplete suppression of mercury vapor from fractured lamps can beachieved by sealing the lamp in a confined space with 10 mg ofunstabilized nanoselenium for 24 hours, either as an impregnated clothdraped over the fractured bulb or as a loose powder in vials.

In summary, based upon the experiments above, the sorbent materials areeffective in capturing and stabilizing mercury. In one embodiment, thesorbent materials are nano-particles selected from a group consistingof: nano-Cu, nano-Ag, nano-Se, nano-S, nano-Ni, nano-Zn, and nano-WS₂are effective in capturing mercury. Most importantly, the sorbentmaterials which are colloidal, unstabilized, nano-Se are most effectivein capturing or absorbing mercury.

However, it should be noted that nano-particles are an example of onetype of sorbent that may be used in the packaging material or package.The additional sorbents may be a micro-scale powder, solution, granular,soluble compound, or sorbent. The sorbent may be activated carbon,impregnated activated carbon, or other impregnated or chemicallymodified activated carbon products. In addition, the soluble compoundmay be thiosulfate.

Referring to FIG. 12, recycling centers may use sorbent materials tocapture and stabilize mercury. When products are placed in the recyclingcontainer 300, the products 310 integrity maybe compromised which willrelease mercury 310A inside the recycling container 300. To capture andstabilize the mercury, the lining 320 of the recycling container 300 isimpregnated or coated with the sorbent materials. Furthermore, inanother embodiment, the sorbent materials are contained in a pouch 330and placed inside a recycling container to capture and stabilize themercury. Also, the sorbent materials may be dispersed on the floors,ceilings, walls, or other surfaces contained within the recycling centeror environment.

To facilitate the capturing of mercury, the recycling containers 300 orreceptacles should have closing mechanisms 340 to suppress the mercury.The reason for this closing mechanism 340 is that the sorbent materialsreact with mercury slowly, so if the receptacle is open, some of themercury will escape while the reaction is proceeding. The combination ofenclosing the recycling container 300 and including the sorbentmaterials 320, 330 leads to the suppression and absorption of mercury.

Referring to FIG. 13, flat-screen televisions 410 and other electroniccomponents also are known to contain mercury. It is contemplated thatthe sorbent materials may be used in reusable packaging 400 forflat-screen televisions or other electronic components, separate sheetsor linings in the packaging for flat-screen televisions or otherelectronic components, or bags lined with sorbent materials containedwithin the flat-screen television or other electronic components. Inaddition, flat screen televisions or other electronic components mayalso contain sorbent materials to capture and stabilize mercury.

A method for producing a recycling container containing sorbentmaterials contains the following steps. First, the sorbent materials areprovided to capture and stabilize mercury. Second, a recycling containeris provided with an inner lining. Third, the sorbent materials arecoated or impregnated onto an inner lining of the recycling container.It should be noted that the lining of the recycling container may beremoved and replaced when containing mercury.

Referring to FIG. 14, sorbent materials may be provided within airfilters or air purifying machines 500 containing air filters 510A,510B.The air filter machine 500 may contain filters 510A,510B, eitherintegrally formed or removable which contain sorbent materials tocapture and stabilize mercury. The air filters and machines may be usedin a residential or commercial building, such as a laboratory.

Referring to FIG. 15, a block diagram for the method 600 for usingsorbent materials to capture and stabilize mercury is illustrated. Themethod 600 contains the following steps. First, the sorbent materialsare provided 610. The sorbent materials, in one embodiment, arenano-particles which are selected from a group consisting of: nano-Cu,nano-Ag, nano-Se, nano-S, nano-Ni, nano-Zn, and nano-WS₂ or anynano-particle used for the capturing of mercury. In a preferredembodiment, the nano-particles are unstabilized, amorphous, andcolloidal. As shown in FIG. 11, the concentration of mercury releasedafter capturing by a nano-particle is highly effective when usingunstabilized, colloidal, nano-selenium.

It should be noted that nano-particles are an example of one type ofsorbent that may be used in the packaging material or package. Theadditional sorbents may be a micro-scale powder, solution, granular,soluble compound, or sorbent. The sorbent may be activated carbon,impregnated activated carbon, or halogen-impregnated activated carbon.In addition, the soluble compound may be thiosulfate.

In another embodiment, the sorbent materials are impregnated, coated,sprayed, dispersed, dipped, or injected onto a carrier material. Thecarrier material may be either a non-porous or porous carrier material.In one embodiment, the carrier material may be a combination of anon-porous and porous material. The carrier material may be selectedfrom a group consisting of: cardboard, textiles, Styrofoam, paper, andplastics.

Next, the sorbent materials are exposed to mercury in an environment620. The environment can be either indoors or outdoors. For example, theindoor environment may be a building, office, dentist's office,laboratory, recycling center, store, residential or commercial building,warehouse, shipping vessel, shipping container, recycling center,container, packaging, storage space, and vehicle or any otherenvironment where mercury is found. More specifically, the mercury maybe spilled on carpeting or porous substrates in the indoor environmentand may require remediation.

For the outdoor environment, it may be a landfill, stadium, office park,or any other outdoor environment where mercury is found. When thesorbent materials are exposed to mercury, the nano-particles absorb orreact with mercury from the environment 630.

Referring to FIG. 16, a block diagram for the method 700 for usingpackaging material or packaging to capture and stabilize mercury isillustrated. The method 700 contains the following steps. The first stepis to remove debris, such as broken bulbs, is removed from the mercuryspillage site. (FIG. 17) and place the debris into a proper containerlined with sorbent materials (FIG. 18). Second, powdered sorbentmaterials are provided for capturing of mercury. (FIG. 18) Third, thesorbent materials are dispersed over a mercury spillage site. (FIG. 19)

Next, a packaging material is provided that contains sorbent materialsfor capturing of mercury 710. In one embodiment, the packaging materialforms a shape of a box which can be used to hold bulbs. Referring toFIG. 20, the packaging material is positioned over mercury spill site tocapture and stabilize mercury 720. To facilitate suppression of themercury, an object may be placed on the packaging material. As a result,the sorbent materials absorb or react with the mercury. After capturingof the mercury, the packaging material is disposed. It should be notedthat the package for this method may be any type of packaging containingsorbent materials for capturing of mercury.

In another embodiment, a kit containing items having sorbent materialsmay be provided to capturing mercury. For example, in FIG. 21, a bag 820or box is used with a cloth 810 impregnated with sorbent materials, apair of gloves 840, and a packet of powdered nano-selenium 830. Theitems are selected from a group consisting of: cloth (FIG. 22), bags,packaging, gloves, paper towels, cardboard, squeegee, eyedropper, ducttape, shaving cream, paint brush, flashlight, or sorbent materials inpowder form, and combinations.

Referring to FIG. 22, a nanosorbent cloth 900 is illustrated which isused for safely cleaning a CFL breakage site. The nanosorbent cloth 900contains, in one embodiment, three layers: a protective layer 900A, anactive layer 900B, and a barrier layer 900C. The protective layer 900Ais porous and undoped to avoid user contact or abrasion of the activelayer 900B. The active layer 900B is porous and doped with sorbentmaterials discussed above for reacting with mercury vapor. The barrierlayer 900C is non-porous to trap mercury vapor to facilitate reaction ofmercury vapor with sorbent materials. These three layers may be combinedor separate and distinct within the nano-sorbent cloth 900. In use, thenanosorbent cloth 900 may be placed over a site containing a broken CFL,such as a carpet, which is releasing mercury vapor, to capture andstabilize the mercury vapor.

The present invention provides a unique method and packaging materialusing sorbent materials to capture and stabilize mercury. In particular,sorbent materials containing colloidal, unstabilized, nano-Se areeffective in capturing mercury from any environment. Based upon theexperiments disclosed, the use of sorbent materials, such as nano-Se, tocapturing mercury is highly effective. In addition, it should be notedthe sorbent materials may be used in a variety of packaging materialsand environments beyond those disclosed herein.

Therefore, while there is shown and described herein certain specificstructure embodying the invention, it will be manifest to those skilledin the art that various modifications and rearrangements of the partsmay be made without departing from the spirit and scope of theunderlying inventive concept and that the same is not limited to theparticular forms herein shown and described except insofar as indicatedby the scope of the appended claims.

What is claimed is:
 1. A packaging material for capturing mercury,comprising: an active layer containing sorbent material for capturingand stabilizing mercury, the sorbent material comprising unstabilizednano-Se particles having high mercury capture; whereby mercury iscaptured and stabilized by the sorbent material.
 2. The packagingmaterial of claim 1, further comprising: a non-porous barrier layer,situated on a top surface of the active layer to slow or prevent thepassage of mercury allowing time for adsorption by the active layer. 3.The packaging material of claim 1, further comprising: a protectivelayer underlying a bottom surface of the active layer, the protectivelayer containing a porous carrier material to prevent skin contact withthe sorbent material of the active layer during handling.
 4. A packagefor products which contain mercury comprising: a sorbent materialeffective for capturing and stabilizing mercury, the sorbent materialcomprising unstabilized nano-Se particles having high mercury capture, acarrier material and the sorbent material being carried on the carriermaterial.
 5. The package of claim 4, further comprising: the sorbentmaterial in a location advantageous for capturing and stabilizingmercury vapor emitted from the product.
 6. The package of claim 4,wherein the carrier material is a liner within the package.
 7. Thepackage of claim 4, wherein the carrier material is porous.
 8. Thepackage of claim 4, wherein the carrier material is non-porous.
 9. Thepackage of claim 4, wherein the carrier material is selected from agroup consisting of: cardboard, textiles, paper, and plastic.
 10. Thepackage of claim 4, wherein: the sorbent material is impregnated withinthe carrier material.
 11. The package of claim 4, wherein: the sorbentmaterial is sprayed onto the carrier material.
 12. The package of claim4, wherein: the carrier material is dipped into the sorbent material.13. The package of claim 4, wherein the carrier material forms a part ofa package for products containing mercury.
 14. The package of claim 13,where the carrier material forms a part of a package for fluorescentbulbs.
 15. The package of claim 13, where the carrier material forms apart of a package for mercury containing waste.
 16. The package of claim4, further comprising: the sorbent material in a pouch in a locationadvantageous for capturing and stabilizing mercury vapor from theproduct.